Aluminum can be formed into building products at the job site and in the factory by roll forming a sheet to the desired configuration. U.S. Pat. No.: 3,791,185 (the Knudson patent) describes a method and machine for making exterior building siding by cold forming an aluminum sheet in a series of paired shaping rolls. Each roll stack imparts a desired shape to the sheet and the opposed roll surfaces define the desired configuration.
Various method and machines are also known in the prior art for forming plastic sheet into building products. Exemplary of the prior art are the following U.S. patents:
U.S. Pat. No.: 4,096,111 (the Sander et al patent) discloses molding a sheet of thermoplastic polymer into a generally rectangular plank with a U-shaped portion projecting from one edge of the plank. Intermediate the edge of the plank and the U-shaped portion, an arcuate depression is formed in the structure during the molding operation to provide a hinge connection between the plank depending U-shaped portion. The U-shaped portion is then bent around the arcuate depression into folded relation with the plank to overlie the edge of the plank and provide a joint for interlocking the bottom of the plank with the top of a similarly formed plank in a tongue and groove arrangement. The molding operation is preferably a vacuum forming method. The disclosed process does not appear to be adapted for use at a job-site.
U.S. Pat. No.: 3,237,361 (the Norman patent) discloses a plastic facing for exterior siding. The plastic facing is attached to a rigid board-like core of gypsum, particle board, plywood or other similar building material. The upper and lower edges of the plastic facing are formed with pendent flaps designed to interlock with complementary pendent flaps on adjacent siding members. The upper flap of a siding unit projects downwardly and outwardly from the top front edge of the siding unit and the lower flap projects inwardly and upwardly from the bottom edge of the siding. When adjacent siding units are assembled in vertical overlapping arrangement, the lower flap of the uppermost siding unit is slipped under and behind the upper flap of the lower siding unit to form an interlocked connection between the two units. No method or machine is disclosed in the patent for making this plastic facing product.
U.S. Pat. No.: 3,281,516 (the Southwick patent) discloses a method and apparatus for forming the plastic facing disclosed in the Norman patent. In this disclosure, plastic sheet is passed through an embossing station where longitudinal fold lines are embossed in the sheet parallel to and at predetermined distances from the edges. The sheet is then heated across its entire width and passed through a preformer station where both edges of the sheet are simultaneously bent along the longitudinal fold lines. In the preformer station opposed die surfaces gradually bend the moving sheet along the fold lines to a cross-sectional configuration approaching the desired shape. After exiting the preformer, the sheet enters a heated former station where a pair of opposed heated die surfaces are used to further form the shape of the sheet towards final configuration. After exiting the former station, the sheet passes into an overbend station which is heated at the entrance end and cooled at the exit end. At the overbend station the formed edge portions are bent back against the sheet to impart the final cross-sectional configuration. The formed sheet then passes through a pair of opposed rotating endless belts which pull the sheet from the machine. The formed plastic sheet is then cut to desired length and laminated to a rigid core to form the finished siding product. The process and machine do not appear to be suited for on-site use because of the machine's size and the nature of the final product.
U.S. Pat. No.: 3,169,274 disclosed another method and machine for making exterior siding from plastic sheet. In this disclosure plastic sheet is heat softened and passed into rather complicated corrugated unit comprising a number of fixed female dies termed "shoes". The hot sheet is stretched and forced into contact with the fixed dies by means of spring loaded movable male die members to form the desired cross sectional configuration. The machine appears complicated, expensive to construct and unsuited for on-site use.
Exterior plastic siding is currently commercially produced by the profile extrusion process. In this process, plastic pellets are melted in a heated extruder. The molten plastic is pumped by action of the extruder screw through a die, the outlet of which conforms to the profile of the desired siding unit. The molten plastic profile is cooled in the die or in an in-line former section to below the softening point of the plastic. The extrusion line required for this process is expensive and complicated in construction and operation. The extrusion die is particularly complicated in construction and precision made, since it must be adjustable to control the thickness of the siding profile uniformly across its width and length. Similarly the extruder is a precision made machine designed to operate at high temperatures and pressures. The equipment required for profile extrusion is not suited for on-site production of exterior siding.
It will become readily apparent that the present invention hereinafter described, provides a novel, efficient and simple means to fabricate exterior siding and other building products with many advantages over the prior art.